Staging
v0.7.0
v0.7.0
https://github.com/torvalds/linux
Tip revision: e49d033bddf5b565044e2abe4241353959bc9120 authored by Linus Torvalds on 04 April 2021, 21:15:36 UTC
Linux 5.12-rc6
Linux 5.12-rc6
Tip revision: e49d033
efi-stub.c
// SPDX-License-Identifier: GPL-2.0-only
/*
* EFI stub implementation that is shared by arm and arm64 architectures.
* This should be #included by the EFI stub implementation files.
*
* Copyright (C) 2013,2014 Linaro Limited
* Roy Franz <roy.franz@linaro.org
* Copyright (C) 2013 Red Hat, Inc.
* Mark Salter <msalter@redhat.com>
*/
#include <linux/efi.h>
#include <linux/libfdt.h>
#include <asm/efi.h>
#include "efistub.h"
/*
* This is the base address at which to start allocating virtual memory ranges
* for UEFI Runtime Services.
*
* For ARM/ARM64:
* This is in the low TTBR0 range so that we can use
* any allocation we choose, and eliminate the risk of a conflict after kexec.
* The value chosen is the largest non-zero power of 2 suitable for this purpose
* both on 32-bit and 64-bit ARM CPUs, to maximize the likelihood that it can
* be mapped efficiently.
* Since 32-bit ARM could potentially execute with a 1G/3G user/kernel split,
* map everything below 1 GB. (512 MB is a reasonable upper bound for the
* entire footprint of the UEFI runtime services memory regions)
*
* For RISC-V:
* There is no specific reason for which, this address (512MB) can't be used
* EFI runtime virtual address for RISC-V. It also helps to use EFI runtime
* services on both RV32/RV64. Keep the same runtime virtual address for RISC-V
* as well to minimize the code churn.
*/
#define EFI_RT_VIRTUAL_BASE SZ_512M
#define EFI_RT_VIRTUAL_SIZE SZ_512M
#ifdef CONFIG_ARM64
# define EFI_RT_VIRTUAL_LIMIT DEFAULT_MAP_WINDOW_64
#else
# define EFI_RT_VIRTUAL_LIMIT TASK_SIZE
#endif
static u64 virtmap_base = EFI_RT_VIRTUAL_BASE;
static bool flat_va_mapping;
const efi_system_table_t *efi_system_table;
static struct screen_info *setup_graphics(void)
{
efi_guid_t gop_proto = EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID;
efi_status_t status;
unsigned long size;
void **gop_handle = NULL;
struct screen_info *si = NULL;
size = 0;
status = efi_bs_call(locate_handle, EFI_LOCATE_BY_PROTOCOL,
&gop_proto, NULL, &size, gop_handle);
if (status == EFI_BUFFER_TOO_SMALL) {
si = alloc_screen_info();
if (!si)
return NULL;
status = efi_setup_gop(si, &gop_proto, size);
if (status != EFI_SUCCESS) {
free_screen_info(si);
return NULL;
}
}
return si;
}
static void install_memreserve_table(void)
{
struct linux_efi_memreserve *rsv;
efi_guid_t memreserve_table_guid = LINUX_EFI_MEMRESERVE_TABLE_GUID;
efi_status_t status;
status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, sizeof(*rsv),
(void **)&rsv);
if (status != EFI_SUCCESS) {
efi_err("Failed to allocate memreserve entry!\n");
return;
}
rsv->next = 0;
rsv->size = 0;
atomic_set(&rsv->count, 0);
status = efi_bs_call(install_configuration_table,
&memreserve_table_guid, rsv);
if (status != EFI_SUCCESS)
efi_err("Failed to install memreserve config table!\n");
}
static u32 get_supported_rt_services(void)
{
const efi_rt_properties_table_t *rt_prop_table;
u32 supported = EFI_RT_SUPPORTED_ALL;
rt_prop_table = get_efi_config_table(EFI_RT_PROPERTIES_TABLE_GUID);
if (rt_prop_table)
supported &= rt_prop_table->runtime_services_supported;
return supported;
}
/*
* EFI entry point for the arm/arm64 EFI stubs. This is the entrypoint
* that is described in the PE/COFF header. Most of the code is the same
* for both archictectures, with the arch-specific code provided in the
* handle_kernel_image() function.
*/
efi_status_t __efiapi efi_pe_entry(efi_handle_t handle,
efi_system_table_t *sys_table_arg)
{
efi_loaded_image_t *image;
efi_status_t status;
unsigned long image_addr;
unsigned long image_size = 0;
/* addr/point and size pairs for memory management*/
unsigned long initrd_addr = 0;
unsigned long initrd_size = 0;
unsigned long fdt_addr = 0; /* Original DTB */
unsigned long fdt_size = 0;
char *cmdline_ptr = NULL;
int cmdline_size = 0;
efi_guid_t loaded_image_proto = LOADED_IMAGE_PROTOCOL_GUID;
unsigned long reserve_addr = 0;
unsigned long reserve_size = 0;
enum efi_secureboot_mode secure_boot;
struct screen_info *si;
efi_properties_table_t *prop_tbl;
unsigned long max_addr;
efi_system_table = sys_table_arg;
/* Check if we were booted by the EFI firmware */
if (efi_system_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE) {
status = EFI_INVALID_PARAMETER;
goto fail;
}
status = check_platform_features();
if (status != EFI_SUCCESS)
goto fail;
/*
* Get a handle to the loaded image protocol. This is used to get
* information about the running image, such as size and the command
* line.
*/
status = efi_system_table->boottime->handle_protocol(handle,
&loaded_image_proto, (void *)&image);
if (status != EFI_SUCCESS) {
efi_err("Failed to get loaded image protocol\n");
goto fail;
}
/*
* Get the command line from EFI, using the LOADED_IMAGE
* protocol. We are going to copy the command line into the
* device tree, so this can be allocated anywhere.
*/
cmdline_ptr = efi_convert_cmdline(image, &cmdline_size);
if (!cmdline_ptr) {
efi_err("getting command line via LOADED_IMAGE_PROTOCOL\n");
status = EFI_OUT_OF_RESOURCES;
goto fail;
}
if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) ||
IS_ENABLED(CONFIG_CMDLINE_FORCE) ||
cmdline_size == 0) {
status = efi_parse_options(CONFIG_CMDLINE);
if (status != EFI_SUCCESS) {
efi_err("Failed to parse options\n");
goto fail_free_cmdline;
}
}
if (!IS_ENABLED(CONFIG_CMDLINE_FORCE) && cmdline_size > 0) {
status = efi_parse_options(cmdline_ptr);
if (status != EFI_SUCCESS) {
efi_err("Failed to parse options\n");
goto fail_free_cmdline;
}
}
efi_info("Booting Linux Kernel...\n");
si = setup_graphics();
status = handle_kernel_image(&image_addr, &image_size,
&reserve_addr,
&reserve_size,
image);
if (status != EFI_SUCCESS) {
efi_err("Failed to relocate kernel\n");
goto fail_free_screeninfo;
}
efi_retrieve_tpm2_eventlog();
/* Ask the firmware to clear memory on unclean shutdown */
efi_enable_reset_attack_mitigation();
secure_boot = efi_get_secureboot();
/*
* Unauthenticated device tree data is a security hazard, so ignore
* 'dtb=' unless UEFI Secure Boot is disabled. We assume that secure
* boot is enabled if we can't determine its state.
*/
if (!IS_ENABLED(CONFIG_EFI_ARMSTUB_DTB_LOADER) ||
secure_boot != efi_secureboot_mode_disabled) {
if (strstr(cmdline_ptr, "dtb="))
efi_err("Ignoring DTB from command line.\n");
} else {
status = efi_load_dtb(image, &fdt_addr, &fdt_size);
if (status != EFI_SUCCESS) {
efi_err("Failed to load device tree!\n");
goto fail_free_image;
}
}
if (fdt_addr) {
efi_info("Using DTB from command line\n");
} else {
/* Look for a device tree configuration table entry. */
fdt_addr = (uintptr_t)get_fdt(&fdt_size);
if (fdt_addr)
efi_info("Using DTB from configuration table\n");
}
if (!fdt_addr)
efi_info("Generating empty DTB\n");
if (!efi_noinitrd) {
max_addr = efi_get_max_initrd_addr(image_addr);
status = efi_load_initrd(image, &initrd_addr, &initrd_size,
ULONG_MAX, max_addr);
if (status != EFI_SUCCESS)
efi_err("Failed to load initrd!\n");
}
efi_random_get_seed();
/*
* If the NX PE data feature is enabled in the properties table, we
* should take care not to create a virtual mapping that changes the
* relative placement of runtime services code and data regions, as
* they may belong to the same PE/COFF executable image in memory.
* The easiest way to achieve that is to simply use a 1:1 mapping.
*/
prop_tbl = get_efi_config_table(EFI_PROPERTIES_TABLE_GUID);
flat_va_mapping = prop_tbl &&
(prop_tbl->memory_protection_attribute &
EFI_PROPERTIES_RUNTIME_MEMORY_PROTECTION_NON_EXECUTABLE_PE_DATA);
/* force efi_novamap if SetVirtualAddressMap() is unsupported */
efi_novamap |= !(get_supported_rt_services() &
EFI_RT_SUPPORTED_SET_VIRTUAL_ADDRESS_MAP);
/* hibernation expects the runtime regions to stay in the same place */
if (!IS_ENABLED(CONFIG_HIBERNATION) && !efi_nokaslr && !flat_va_mapping) {
/*
* Randomize the base of the UEFI runtime services region.
* Preserve the 2 MB alignment of the region by taking a
* shift of 21 bit positions into account when scaling
* the headroom value using a 32-bit random value.
*/
static const u64 headroom = EFI_RT_VIRTUAL_LIMIT -
EFI_RT_VIRTUAL_BASE -
EFI_RT_VIRTUAL_SIZE;
u32 rnd;
status = efi_get_random_bytes(sizeof(rnd), (u8 *)&rnd);
if (status == EFI_SUCCESS) {
virtmap_base = EFI_RT_VIRTUAL_BASE +
(((headroom >> 21) * rnd) >> (32 - 21));
}
}
install_memreserve_table();
status = allocate_new_fdt_and_exit_boot(handle, &fdt_addr,
initrd_addr, initrd_size,
cmdline_ptr, fdt_addr, fdt_size);
if (status != EFI_SUCCESS)
goto fail_free_initrd;
if (IS_ENABLED(CONFIG_ARM))
efi_handle_post_ebs_state();
efi_enter_kernel(image_addr, fdt_addr, fdt_totalsize((void *)fdt_addr));
/* not reached */
fail_free_initrd:
efi_err("Failed to update FDT and exit boot services\n");
efi_free(initrd_size, initrd_addr);
efi_free(fdt_size, fdt_addr);
fail_free_image:
efi_free(image_size, image_addr);
efi_free(reserve_size, reserve_addr);
fail_free_screeninfo:
free_screen_info(si);
fail_free_cmdline:
efi_bs_call(free_pool, cmdline_ptr);
fail:
return status;
}
/*
* efi_get_virtmap() - create a virtual mapping for the EFI memory map
*
* This function populates the virt_addr fields of all memory region descriptors
* in @memory_map whose EFI_MEMORY_RUNTIME attribute is set. Those descriptors
* are also copied to @runtime_map, and their total count is returned in @count.
*/
void efi_get_virtmap(efi_memory_desc_t *memory_map, unsigned long map_size,
unsigned long desc_size, efi_memory_desc_t *runtime_map,
int *count)
{
u64 efi_virt_base = virtmap_base;
efi_memory_desc_t *in, *out = runtime_map;
int l;
for (l = 0; l < map_size; l += desc_size) {
u64 paddr, size;
in = (void *)memory_map + l;
if (!(in->attribute & EFI_MEMORY_RUNTIME))
continue;
paddr = in->phys_addr;
size = in->num_pages * EFI_PAGE_SIZE;
in->virt_addr = in->phys_addr;
if (efi_novamap) {
continue;
}
/*
* Make the mapping compatible with 64k pages: this allows
* a 4k page size kernel to kexec a 64k page size kernel and
* vice versa.
*/
if (!flat_va_mapping) {
paddr = round_down(in->phys_addr, SZ_64K);
size += in->phys_addr - paddr;
/*
* Avoid wasting memory on PTEs by choosing a virtual
* base that is compatible with section mappings if this
* region has the appropriate size and physical
* alignment. (Sections are 2 MB on 4k granule kernels)
*/
if (IS_ALIGNED(in->phys_addr, SZ_2M) && size >= SZ_2M)
efi_virt_base = round_up(efi_virt_base, SZ_2M);
else
efi_virt_base = round_up(efi_virt_base, SZ_64K);
in->virt_addr += efi_virt_base - paddr;
efi_virt_base += size;
}
memcpy(out, in, desc_size);
out = (void *)out + desc_size;
++*count;
}
}